This invention relates to a rotationally molded article comprising an inner member extending across the inner space of the article. In one aspect the invention relates to a method of rotationally molding an article.
Baffles with openings therethrough are used in containers such as vehicle fuel tanks to dampen the forces of surging liquid during sudden stops. Without the dampening effect of baffles, it is sometimes possible for such surges to apply sufficient force to overload a tank thus increasing the danger of rupture and loss of liquid or vapor therefrom with the resulting danger of fire or release or dangerous fumes.
The installation of baffles in one piece molded plastic tanks is quite difficult. It is impossible, of course, to install such baffles after forming the tank. If baffles are formed by molding a wall of the container around a tapered rib on the wall of the mold thus forming a hollow inwardly extending protrusion, several problems combine to cause difficulty in molding. The inwardly extending protrusion is necessarily double walled wasting valuable space. The wall of the container generally is thinner at the top of such a tapered rib and thus is the weakest portion of the container and the remainder of the container must be made heavier than desirable in order to provide the necessary strength at the weak point which also increases the cost of the container due to the large amount of resin required. Such protrusions often cause mold release problems. For these reasons in most instances there is a practical limitation on such a protrusion to limit it to a height of about 1/4 to 1/3 of that of the container.
Where the container is very shallow it is possible to extend such a protrusion entirely through the container but even in this instance the difficulties of thinning of the container wall, difficult mold release and loss of tank volume remain.
An object of the invention is to provide baffles in rotational molded containers without the hollow protrusions of the prior art. Another object of the invention is to rotationally mold containers having internal baffles without producing unnecessary thinning of the container walls, unusual mold release problems and without unnecessarily losing tank volume. Another object of the invention is to rotationally mold containers having rigidly supported internal baffles with a minimum use of resin.
According to the invention a rotationally molded article is produced having a member extending across the interior space thereof, the inner member being attached at one location by support means molded into the wall of the article and at another location by engagement with an inner portion of the wall.